Caudipteryx

The discovery of the bizarre theropod Caudipteryx in 1998 was an exciting event for the science of paleontology. Scientists had long realized that if birds evolved from dinosaurs, somewhere along the line there ought to be a dinosaur with half a wing - a limb that was more than a simple dinosaur arm but not developed into a fully functional wing. Caudipteryx was just such an animal. Here was a long-legged, gracile theropod dinosaur with well-developed but short arms - and impressions of small feathered wings trailing behind its forearms.

How Caudipteryx used these "wings" is a puzzle. They were too small to have been used for flight. Perhaps they helped the animal catch insects, or they may have combined with the tuft of feathers on the tail to make a stunning sexual display. Whatever their function, we can now be certain that an animal with half a wing once existed.

The exquisite state of preservation of Caudipteryx from the Liaoning deposits reveals a wealth of detail. Not only were there long feathers on Caudipteryx's arms and tail, but shorter downy feathers covered most of the body. The head was small and rounded. Long, sharp teeth were restricted to the very front of the mouth and projected more forward than downward. Perhaps they were part of an early horny beak. In the gizzard region there was a collection of tiny pebbles, or gastroliths, that the animal swallowed to help it grind up food - yet another birdlike feature. Caudipteryx had a well-developed wishbone, a feature seen only in birds and the theropods. Caudipteryx's long legs suggest that it was a speedy runner that probably made a living chasing after insects or other small animals.